Ultra high step-up converters with reduced diode stresses sharing

Novel high step-up DC/DC converters are proposed in this paper. Through employment of coupled inductor and switched capacitor, the proposed converters achieve high step-up conversion ratio without operating at extreme duty ratio. Due to recycle of leakage energy, the efficiency is improved and the large voltage spike on switch is alleviated, which makes a low-voltage-rated MOSFET with low R_DS(ON) can be adopted for reductions of conduction losses. In addition, the selection of diodes is convenient and cheap because all the reduced voltage stresses on diodes are the same. Finally, a 200 W prototype circuit with 12 V input and 400 output V output is implemented to verify the performance, and the highest efficiency is 96.89%.